Controlling fuel vapor in vehicle fuel tanks has long been an objective for automobile manufacturers and suppliers of fuel systems components. Fuel vapor can be created in the fuel tank by temperature differences between the fuel tank and liquid fuel from a fuel pump, as well as by sloshing and agitation of the fuel tank during normal vehicle operation. The fuel vapor collects in the space above the fuel within the tank and is normally released through one or more vent valves located within the wall of the fuel tank. This prevents pressurization of the tank or the creation of a vacuum therewithin as a result of fluctuations in fuel volume due to changes in temperature, atmospheric pressure, or the drop in fuel level as it is drawn off by the engine.
With the increasing requirements and regulations to reduce emissions, where vent valves used to be mounted through separate apertures in the fuel tank from the fuel pump flange, it now becomes advantageous to incorporate them with the fuel pump mounting flange thereby eliminating the need for additional holes through the tank and potential vapor emission sources.
Such practice is known in the art to incorporate the vent valve in the modular flange as mentioned above. Current valve designs utilize a valve housing that attaches to the modular flange with an O-ring seal disposed there between the housing and the flange for reducing emissions. When actuated, the valve float assembly makes contact with the upper wall of the valve housing, sealing off the vapor/fuel outlet through the valve housing. Unfortunately there is the potential that vapor or fuel may still bypass the valve housing and O-ring seal either through a faulty seal or permeation, even when the valve is in the closed position, creating undesired emissions. It is therefore more advantageous to incorporate a vent valve with the modular flange in a manner which would eliminate the need for the second seal between the valve housing and the modular flange, by creating a valve assembly that operates directly against the modular flange, thereby reducing a potential emission source, as well as lowering production costs and minimizing parts.